Sacra Via: the oldest and most famous street in Rome, it and the Nova Via (q.v.) being the only streets within the city called viae before the imperial period. The adjective almost always precedes, except in poetry (for exceptions, see Pliny HN 19.23; Suetonius Vitel. 17; Asconius ad Cic. Milon. 42 [Stangl 41]; CIL 6.9239, 9418, 9549; ILS 7700; regionary catalogues, Regio IV). There was even a common tendency to run the two words together into a single word in pronunciation (Festus 372L). Mentions of it are very frequent in all periods, but for the most part not informative. It is listed in Regio IV in the regionary catalogues.

The Sacra Via was commonly believed to extend from Summa Sacra Via, where were clustered the Temple of the Lares (Augustus RG 19), the house of the rex sacrorum (Festus 372L), and the Temple of Iuppiter Stator (Plutarch Cic. 16.3), to the Regia (Festus 372L) and Fornix Fabianus (Cicero Planc. 17). Three times it is called Sacer Clivus (Horace Car. 4.2.35; Martial 1.70.5, Martial 4.78.7), but only in poetry, and to go from Summa Sacra Via to the forum was Sacra Via descendere (Cicero Att. 4.3.3; Horace Epod. 7.7). But Varro (Varro Ling. 5.47) and Festus (Festus 372L) are explicit that the Sacra Via really began at the Sacellum Streniae on the Carinae and extended from the Regia in arcem. Varro explained this by saying sacra were carried from the sacellum to the arx every month, and the augurs setting out from the arx were accustomed to inaugurare by the Sacra Via. This must mean that in the late republic and early empire on the Ides, which were sacred to Jupiter, the priests bringing sacra from the Sacellum Streniae had to make a sharp turn at Summa Sacra Via (cf. the course of Nova Via) and probably had to ascend the Capitoline by the stair known as the Gradus Monetae (later replaced by the Scalae Gemoniae), for the only road up the Capitoline on this side was the Clivus Capitolinus. Unless the clivus was considered part of Sacra Via, which no one suggests (cf., e.g., Pliny HN 19.23), the ascent must have been made by the stair. This really creates no difficulty, except as the Scalae Gemoniae came to be associated with disgrace and violence. But the sacra in question were the idulia sacra (Festus 372L) and involved a sheep, the idulis ovis (Paulus ex Fest. 93L; Macrobius Sat. 1.15.16). This was a gelding, alba. . . grandior agna (Ovid Fast. 1.55-56, Ovid Fast. 1.587-88), and it was sacrificed by the Flamen Dialis and the entrails offered at the Temple of Iuppiter Optimus Maximus (Ovid Fast. 1.55-56, Ovid Fast. 1.587-88). One must ask why it should have been taken to the other peak of the Capitoline first. Perhaps it is because the worship of Jupiter was older on the higher peak.

The course and level of the Sacra Via varied considerably in antiquity, as can be seen dramatically at the Arch of Titus, where the footing of the arch stands well above the Augustan pavement that has now been exposed for most of the length of the street between the Regia and Summa Sacra Via. As it was always the principal route from the Palatine to the Forum Romanum (Plutarch Cic. 22.1; Tacitus Hist. 3.68; Cass. Dio 64.20.3, Cass. Dio 78.4.3), in the republican period it probably followed a relatively straight course from Summa Sacra Via to the Regia. Under the empire ambitious building programs, such as those of Nero for the Domus Transitoria and Domus Aurea and that of Maxentius when a serious conflagration made a large area available for redevelopment, may well have forced it to deviate. After the construction of the Arch of Titus, this at Summa Sacra Via and the Fornix Fabianus at the Regia (no one ever uses the term Ima Sacra Via) must have seemed terminals. Herodian (Herodian 2.9.5 and Herodian 7.6.9) has been taken to indicate that in his day a stretch was known as Media Sacra Via, but the case is weak.

Brown's excavations in and around the Regia led him to conclude that in the time of the kings and the early republic the Sacra Via "sloped downward on a long curve from the upper Palatium to its northeast, then between Vesta and the Regia along Castor and Pollux, whence it crossed the forum beside the Doliola to the Comitium" (Gnomon 56 [1984]: 381-82 [F. E. Brown]), and that it was only after the pavement of the forum in 179 B.C. that the Sacra Via ran along the north side of the forum. It is difficult to follow Brown in this. The brook now buried under the Sacra Via on the Velia must always have determined the course of a thoroughfare, with first a path and then a road running along it bringing traffic into the forum. If it divided just above the Regia, the road will not have deviated to follow it to the northwest, but will have crossed it on a bridge. If another path developed along the branch to make a forked entrance to the forum, the more direct route will still have been the real Sacra Via, and it is difficult to see the Gradus Monetae as anything but an archaic approach to the northeast height of the Capitoline dictated by the necessities of religion and ritual, ascending the hill steeply in a straight line. Brown's new line will be only auxiliary. For Plautus (Plautus Curc. 470-75) proves that one could stroll along the northeast side of the forum from the Comitium to Forum Infimum while the Cloaca was still an open trench across the middle.

For the Sacra Via before the time of Augustus, our archaeological evidence is poor and fragmentary. In the late republican period it seems to have been lined with shops in front of houses from just beyond the Regia to Summa Sacra Via. The rebuilding of the Regia in 36 B.C. and the building of the Temple of Divus Iulius in the next few years did little to change it. Marius had already built his Temple of Honos et Virtus across from the Regia, but he also had a house there (see Domus, C. Marius), and Horace shows that in his day it was still the shopping street par excellence of Rome. The Augustan pavement has now been uncovered, 5 m wide, for most of the length of this sector; it rises from 12.60 meters above sea level at the northeast corner of the Temple of Divus Iulius to 28.30 meters above sea level at its crest east of the Arch of Titus. Some of its pavement has been found underlying the steps of Hadrian's Temple of Venus et Roma. How much change there was for the creation of the Domus Transitoria is not clear, but after the fire of A.D. 64 we see a considerable rise in level and the construction of handsome arcades on both sides of the street that fronted vast structures similar to the Porticus Minucia Frumentaria (q.v.), which must have served as offices for parts of the bureaucracy that ran the empire. These led to a grand colonnaded cour d' honneur at the top of the Velia, with the Colossus of Nero as its center and focus. Later Domitian converted at least some of the arcaded buildings flanking the Sacra Via into the Horrea Piperataria (q.v.), but without change in the Sacra Via. Change came with Hadrian's construction of the Temple of Venus et Roma (see Venus et Roma, Templum) to replace Nero's colonnaded court, after which time the Sacra Via became a broad avenue, flanked by porticoes and shops, those on the northeast side being eventually replaced by the Basilica Constantini (q.v.). Unfortunately, this avenue was removed in 1899 in the belief that it was medieval and the Augustan pavement uncovered. Consequently, all the imperial buildings now seem to float on their foundations. There is no evidence that the continuation of the Sacra Via beyond the Arch of Titus in the direction of the Meta Sudans was ever called, or thought of as part of, Sacra Via.

On the Ides of October, after the sacrifice of the October horse at the Altar of Mars in the Campus Martius, the head of the horse was cut off and decorated with bread, and the Sacravienses and Suburanenses battled for the possession of it. If the Sacravienses were victorious, they nailed the head to a wall of the Regia. It is not clear exactly who made up these two factions or how they were marshaled. The struggle for possession of the head presumably took place in the Forum Romanum (Festus 190L, Festus 246L; Plutarch Quaest. Rom. 97).

As one ascends the Sacra Via from the forum, after passing the Basilica Paulli one has on the left the Temple of Antoninus and Faustina, the archaic Sepulcretum, remains of republican houses, the so called Tempio di Divo Romolo, a medieval loggia, and the Basilica Constantini. On the right are the Regia, remains of houses and shops between the road and the Atrium Vestae, a medieval hemicycle facing the loggia, and the great forest of piers faced with brickwork commonly called the Porticus Margaritaria (q.v.). All these are, in effect, public buildings, or publicly controlled, and attest to the great importance that the Sacra Via apparently always had.